The Chiefs have made a major upgrade at quarterback with the steady Alex Smith. / Howard Smith, USA TODAY Sports

by Lindsay H. Jones, USA TODAY Sports

by Lindsay H. Jones, USA TODAY Sports

ENGLEWOOD, Colo. â?? In recent years, four wins through the first half of the season would put an AFC West team right in contention to win the division and nab a playoff spot.

Not this year. Mediocre won't be good enough to make the playoffs in what has suddenly become the strongest division in the NFL.

That's the challenge right now for the San Diego Chargers, at 4-4 heading into Sunday's game against Denver. It's only early November, and yet the Chargers trail the Broncos (7-1) by three games, and the undefeated Chiefs (9-0) by five games.

"It's quickly gone from a division that maybe was looked at from the outside as not necessarily one of the best divisions in football over the last three, four years. Now it's probably being considered one of the better ones, and in large part, because of Denver and Kansas City," San Diego quarterback Philip Rivers said. "We can't really worry about those guys other than when we play them. We're not necessarily trying to play the catch-up game and see what they're going to do."

Indeed, the four teams in the AFC West have combined for 23 wins over the first nine weeks of the season, two more wins than the next-best division, the NFC West. The AFC West has got there in part by dominating against the dismal NFC East this season â?? with a record of 9-3 against the Cowboys, Giants, Redskins and Eagles though the first half of the year.

It's all led to what should be a crazy November out west, starting with Sunday's game in San Diego. The Broncos will then play the Chiefs twice in the following two weeks. The Chiefs, currently on their bye week, will play host to the Chargers in Week 12, between the two games against Denver.

"I think the nice thing for us, built in there, is another team in the division that's been getting a lot of attention as well," Kansas City quarterback Alex Smith said this week. "There's no room to relax. We're neck and neck, and we've still got two big games ahead of us with [Denver] and a lot of games left ahead in general."

NBC has already snatched the first of the two games between the Broncos and Chiefs, next week at Denver, for its prime time schedule, bumping a game between the Aaron Rodgers-less Green Bay Packers and New York Giants out of the coveted national slot. Flexing a game between AFC West rivals, especially the Chiefs, was unthinkable just a few months ago.

"Our division is always tough, but it is good to see that we have one of the toughest divisions," Denver middle linebacker Wesley Woodyard said.

So how did the AFC West morph from an NFL punchline, which it most certainly was in 2011, when three teams finished tied atop to the division at 8-8, to a conference power?

It's easy. Change the coach. Change the quarterback.

Each of the teams in the AFC West have replaced their head coach since 2011, starting with the Broncos, who fired Josh McDaniels late in the 2010 season and hired John Fox. The Oakland Raiders were next, hiring Dennis Allen off Fox's staff in Denver to replace Hue Jackson in 2012. The Chiefs and Chargers were next, replacing Romeo Crennel and Norv Turner with Andy Reid and Mike McCoy, respectively, this year.

Remember the start of the 2011 season? On opening day, the AFC West starting quarterbacks were Kyle Orton (Denver), Matt Cassel (Kansas City), Jason Campbell (Oakland) and Rivers. Only Rivers remains after all of the change, and there is no question the Broncos (with Peyton Manning) and Chiefs (with Smith) have upgraded. Even Oakland, who traded for and then traded away Carson Palmer in the time since, is in a better spot now with Terrelle Pryor.

But don't expect any of those quarterbacks to be rooting for their divisional counterparts. This isn't college football, where team pride is trumped only by conference pride.

"I mean, you want to win your division, so I don't necessarily pull for us to have a great division, you know? You just want to find a way to win it, so I don' think there's anything that you want to say, 'Hey, I hope Denver, Kansas City and Oakland all win a ton of games so our division can look good.' I'd rather that not be the case," Rivers said. "But there is a respect factor within your division of what these teams are doing. You can't deny how impressive those two teams' starts have been."